From d6f7b2d99bdbcc29e8784185612282a508cc3e84 Mon Sep 17 00:00:00 2001 From: Martin Rudalics Date: Fri, 22 May 2026 19:33:57 +0200 Subject: [PATCH] Save/restore old_buffer slot via window configurations (Bug#81097) With Emacs 31 the old_buffer slot of a window gets overwritten with the buffer unshown in that window when that window is deleted. Fset_window_configuration triggers that when calling delete_all_child_windows. If a window configuration gets saved and restored in one and the same redisplay cycle, the change time stamps of the window and its frame will be equal and 'window-buffer-change-functions' may wrongly decide that the window's buffer has not changed because its buffer and old_buffer slots refer to the same buffer (Bug#81097). Fix that by saving and restoring the old_buffer slot. * src/window.c (struct saved_window): Add 'old_buffer' slot. (Fset_window_configuration): Restore old_buffer slot. (save_window_save): Save old_buffer slot. --- src/window.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/src/window.c b/src/window.c index 3dbf1530d78..792c43d0555 100644 --- a/src/window.c +++ b/src/window.c @@ -7611,7 +7611,7 @@ struct saved_window { union vectorlike_header header; - Lisp_Object window, buffer, start, pointm, old_pointm; + Lisp_Object window, buffer, old_buffer, start, pointm, old_pointm; Lisp_Object pixel_left, pixel_top, pixel_height, pixel_width; Lisp_Object left_col, top_line, total_cols, total_lines; Lisp_Object normal_cols, normal_lines; @@ -7835,6 +7835,7 @@ the return value is nil. Otherwise the value is t. */) /* If we squirreled away the buffer, restore it now. */ if (BUFFERP (w->combination_limit)) wset_buffer (w, w->combination_limit); + wset_old_buffer (w, p->old_buffer); w->pixel_left = XFIXNAT (p->pixel_left); w->pixel_top = XFIXNAT (p->pixel_top); w->pixel_width = XFIXNAT (p->pixel_width); @@ -8221,6 +8222,7 @@ save_window_save (Lisp_Object window, struct Lisp_Vector *vector, ptrdiff_t i) wset_temslot (w, make_fixnum (i)); i++; p->window = window; p->buffer = (WINDOW_LEAF_P (w) ? w->contents : Qnil); + p->old_buffer = w->old_buffer; p->pixel_left = make_fixnum (w->pixel_left); p->pixel_top = make_fixnum (w->pixel_top); p->pixel_width = make_fixnum (w->pixel_width);